Packet transmission device and packet transmission method

The packet transmission device including: a first and a second storage module to store a token value; a token controller to add a predetermined token value to a first total token value, and subtract a predetermined token value from the first total value in response to the output of the packet; an overrun state controller to add an excess of the first total token value over a predetermined upper limit value to a second total token value, in the case where the first total token value added by addition control is greater than or equal to the predetermined upper limit value; and an underrun state controller to subtract a predetermined token value from the second total token value and add the subtracted token value to the first total token value, in the case where the subtracted first total token value is less than the predetermined upper limit value.